Title

Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

Deflection analysis of piles under lateral live loads in various soil conditions is presented herein. Field testing of lateral capacity was conducted at four test sites in California and Nevada, where weak surface soil provides insufficient lateral capacity for helical piles. In these areas of weak surface soil, as defined by field or laboratory testing, the most feasible solution for a foundation system may be the implementation of a deep foundation system such as a pier and grade beam or helical pile (HP) foundation system. Helical pile diameters that normally range from 1-1/2 to 4 inches provide minimal support when subject to lateral loads. An alternate structural member introduced as a Lateral Restraint Device (LRD), has been developed which increases the lateral capacity of the helical pile foundation system by increasing the soil-structure contact bearing area of the laterally loaded soil near the ground surface. Data was compiled at four testing locations during the load testing of various length and diameter Lateral Restraint Devices. Helical pile and Lateral Restraint Device systems have limited published data for methods to determine the capacity of the system based on variable soil conditions. In addition to providing data collected during field testing that verifies the capacity of an LRD per unit area, a correlation of capacity at 1/2-inch deflection to Standard Penetration Test blow count data was established. This research demonstrates that lateral capacities of helical piles increased substantially with the implementation of an LRD, which can be addressed early in a site investigation with correlation to blow count data and laboratory testing programs.

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Deflection analysis of piles under lateral live loads in various soil conditions is presented herein. Field testing of lateral capacity was conducted at four test sites in California and Nevada, where weak surface soil provides insufficient lateral capacity for helical piles. In these areas of weak surface soil, as defined by field or laboratory testing, the most feasible solution for a foundation system may be the implementation of a deep foundation system such as a pier and grade beam or helical pile (HP) foundation system. Helical pile diameters that normally range from 1-1/2 to 4 inches provide minimal support when subject to lateral loads. An alternate structural member introduced as a Lateral Restraint Device (LRD), has been developed which increases the lateral capacity of the helical pile foundation system by increasing the soil-structure contact bearing area of the laterally loaded soil near the ground surface. Data was compiled at four testing locations during the load testing of various length and diameter Lateral Restraint Devices. Helical pile and Lateral Restraint Device systems have limited published data for methods to determine the capacity of the system based on variable soil conditions. In addition to providing data collected during field testing that verifies the capacity of an LRD per unit area, a correlation of capacity at 1/2-inch deflection to Standard Penetration Test blow count data was established. This research demonstrates that lateral capacities of helical piles increased substantially with the implementation of an LRD, which can be addressed early in a site investigation with correlation to blow count data and laboratory testing programs.